A sedentary lifestyle is believed to be the major cause of weight problems in Maltese children as a new Canadian study on obesity in 34 countries confirms they rank among the heavyweights.

Of the Maltese children surveyed, just 25.6 per cent were physically active - one of the lowest figures among the surveyed countries. No less than 42.7 per cent reported watching three or more hours of television during the average weekday.

Increasing physical activity and reducing TV viewing should be the focus of strategies aimed at preventing and treating overweight and obesity in youth, the study concludes.

The three countries with the highest prevalence of overweight youth aged 10-16 were found to be Malta (25.4 per cent), the US (25.1 per cent) and Wales (21.2 per cent).

The countries with the highest incidence of obesity were Malta (7.9 per cent), the US (6.8 per cent) and England (5.1 per cent), according to the report by Queen's University in Kingston.

"Canada has ranked in fifth place of overweight children and I believe there is huge scope for concern, let alone Malta which has come on top," lead researcher Ian Janssen told The Times yesterday.

The study is based on the World Health Organisation's 2001-2002 Health Behaviour in School-Aged Children, which had put Maltese children close to the top of the overweight and obesity rankings.

But the Canadian research also factors in new data on the international body mass index standards for children and focuses on the potential links with obesity, which were not touched upon in the WHO report.

Sedentary behaviours such as television viewing and physical inactivity were strongly correlated with being overweight, and this was consistent in most of the 34 countries, Dr Janssen said.

"I think that's a very powerful observation when you can show these consistent relationships in countries with different backgrounds and different cultures and different population groups," he added.

Overall, in 77 per cent of the countries examined, at least 10 per cent of young people were overweight, while in a fifth of the countries, at least three per cent were considered obese. The survey did not include Asian or African countries.

The study, which is to appear in the May issue of Obesity Reviews, has some surprising observations.

"Besides, those who ate candy and chocolate more frequently were less likely to be overweight. That was unexpected, as you can guess," Dr Janssen said.

"But that definitely doesn't mean you can eat all of the chocolate you want. This was measuring the frequency of consumption and not the total portion sizes."

Of the Maltese children surveyed, 38 per cent were found to have a high sweet intake and a quarter consumed too many soft drinks.

However, it is inactivity that experts blame most for increased obesity rates among children and young people, which have gone up as much as fivefold in the last 20 years or so.

Asked whether he believed overweight children would eventually grow out of their fat in their adulthood, Dr Janssen said such statistics were indeed cause for concern.

"Children are also susceptible to having high blood pressure and high cholesterol. They are also likely to pave the way for big problems in their adult life," he said.

The problem of overweight in school-aged youth requires increased efforts and partnerships at all levels, including regional and national governments. The Maltese government should ensure that the necessary facilities and infrastructure is in place to allow people to exercise, Dr Janssen said. The Canadian government has published its own Physical Activity Guide in this respect.

Obesity is clearly becoming an epidemic in Malta with a series of surveys putting the Maltese among the top of the lumpy league.

In data published last month, Maltese children aged between seven and 11 were considered to be the most obese and overweight in the European Union.

The message does however seem to be getting across in some quarters. Health Minister Louis Deguara has said that plans are underway to set up a hospital-based paediatric obesity clinic to address the worrying cases of child obesity.